BitTorrent Inc., the makers of uTorrent and the BitTorrent Mainline client, have been sued for infringement of a file-sharing related patent. According to the complaint, the BitTorrent clients infringe on the rights of San Francisco-based company Tranz-Send Broadcasting Network. The company demands compensation and if the court agrees, this case could have a disastrous impact on the BitTorrent landscape.

By now we’ve become accustomed to copyright infringement lawsuits, where people are suspected of illegally distributing movies and music using BitTorrent.

However, according to a lawsuit filed at a U.S. District Court this week, BitTorrent is also an infringement in its own right.

Tranz-Send Broadcasting Network filed a complaint at the court this week where it alleges that BitTorrent is infringing on a patent originally filed in April 1999. The company claims to have suffered significant losses and wants to be compensated for the ongoing patent infringement.

“By making, operating, using and/or selling [uTorrent and BitTorrent Mainline] and or other software, BitTorrent has infringed and continues to infringe, contribute to the infringement, or induce the infringement of at least claim 1 of the ‘944 patent,” the complaint reads.

The patent in question is titled “Media file distribution with adaptive transmission protocols” and was granted in November 2007. It describes a file-sharing system consisting of a file database, a transfer client and a distribution server.

“A server/client media file distribution system is provided in which the server system is adapted to receive transmission requests from clients, status information from a network, and protocol information from each client,” company writes in the patent abstract.

“The server, based upon this information, adaptively transmits a given media file stored therein to one or more clients using the optimal transmission speed and/or network protocol based on the network status information and protocol information,” the abstract adds.

The above is certainly not how most people would describe BitTorrent, but its is up to the District Court Judge to assess the validity of the patent infringement claim. Aside from BitTorrent Inc., Tranz-Send Broadcasting Network have also sued Kontiki Inc. on similar grounds.

Kontiki offers a media content delivery technology that is hybrid of central servers and P2P transfers. Unlike BitTorrent Inc, Kontiki’s user base mostly consists of businesses who can use the software to stream and distribute video. According to the complaint, this software also infringes on the aforementioned patent.

Although it’s not easy for an outsider to assess whether the case holds water or whether it’s classic patent trolling, the fall-out could spread far and wide.

Together, the two BitTorrent clients mentioned in the lawsuit have a user-base of more than 100 million users worldwide. If BitTorrent Inc. is suddenly required to pay royalties for each and every download, this will drastically impact the company’s operations. Not to mention the spill-over effect it may have on other BitTorrent software companies.

BitTorrent Inc. was asked for a comment on the lawsuit, but TorrentFreak was told that the company currently has nothing to add.